=rem #3527 Throw away system message delivery state when new UID from a remote Address is detected
(cherry picked from commit cc159195128c5bd896b9928bf461c858551313b5)
=rem #3527 Fail fatally when negative acknowledgement is unfulfillable
(cherry picked from commit d85039c1a6f141ec99c6f19ff94703d6c4e24660)
=rem #3527 Take actor system uid into consideration in remote watch

* When actor system was restarted quickly the new system replied to
  heartbeats and Terminated was never triggered for actors in old
  system.
* Solved by sending an extra Watch system message when first hearbeat
  is received for an address and when a change of system uid is detected.
(cherry picked from commit 637598a28bc5aafaca27b801f442cf9b20009807)
=rem #3527 Correction of match in reWatch
(cherry picked from commit 12a442f7d062fa5f72de6bf39e48f7604836e8ec)
Merge pull request #1670 from akka/wip-3527-remote-watch-uid--2.2-patriknw

=rem #3527 Take actor system uid into consideration in remote watch (backport)